The field of the invention is wireless information devices and more specifically wireless devices for automatically obtaining location based information related to machines when a wireless device is placed within proximity of the machines.
There are many industries where electronic interfaces have been developed to facilitate monitoring or control or both system monitoring and control. For instance, in the industrial automation industry, a manufacturing plant may include several thousand different machines arranged to form a plurality of machine lines that cooperate to produce one or more products. In this case, each machine or a sub-set of machines may be equipped with an interface including a processor, some type of information output device and some type of information input device. The output device is often a display screen for displaying text, graphics, etc., and the input device is typically a keyboard.
Because of the nature of industrial automation, some industrial facilities have adopted policies requiring at least some level of local or location specific interfacing and control. In industrial control, many (e.g., tens or perhaps even hundreds) machines may be positioned along a machine line so that improper performance of or damage to one machine affects operation of a large number of related downstream machines. In addition, improper machine operation, given unforeseen circumstances, may result in injury to facility employees proximate the malfunctioning machine or proximate downstream machines. In these cases, if remote control were allowed, an operator may adjust one machine believing that some other similar machine is being adjusted with unintended and potentially costly results.
In an effort to avoid unintended results, most automated facilities require operators to be located adjacent or proximate a machine prior to altering machine operation. This proximity requirement is enforced by providing machine monitoring and controlling interfaces proximate associated machines. More specifically, the interfaces are typically placed in positions that enable an interface operator to observe machine operation prior to, during and after adjustment of machine operating characteristics. Here the interfacing is local despite remote or centralized processing. In this manner, an operator can essentially simultaneously observe operation of a particular machine and the information provided by an interface associated with the particular machine. This “dual viewing” capability facilitates a far more comprehensive understanding of machine conditions and enables the operator to quickly determine if control alterations have desired effects.
Requiring even basic interfaces at each machine or adjacent logically related sub-sets of machines is relatively expensive as each interface typically requires a display of some type and at least a set of control buttons or a keyboard of some type. To minimize costs many control systems are designed to provide pseudo-local or multiplexed control where one interface may be provided for several proximate machines. For instance, one interface may be provided for ten proximate machines.
Multi-machine interfaces represent a tradeoff between cost and functionality. TO this end, as indicated above, unfortunately, the “dual viewing” (i.e., simultaneous view of a machine and an associated interface) capability afforded by providing interfaces as close as possible to associated machines is hampered when the number of interfaces is less than the number of machines within a facility. Thus, in the case above, where a single interface is provided for ten separate but proximate machines, the interface may not be located in an optimal position for observing operation of a sub-set of the ten machines while simultaneously viewing the interface.
In addition, where a single interface is provided for more than one machine, the interface has to be relatively more complex than an interface provided for a single machine. To this end, to avoid confusion and unintended changes to machine operation, it is generally accepted that an interface should only display information corresponding to a single machine or a related sub-set of machines at any given time. For example, where a single interface is provided for accessing information corresponding to and controlling ten logically related machines, if the interface were programmed to provide information and controls for two or more of the machines at one time, an interface operator may examine data corresponding to one of the ten machines believing that the examined data corresponds to another of the ten machines or worse, the operator may adjust control of one of the ten machines believing that the operator is controlling another of the ten machines.
To avoid this type of confusion and related control errors, multi-machine interfaces are typically programmed to so that information and control tools corresponding to only a single one of the machines associated with an interface are provided at any time. Thus, multi-machine interfaces generally require some type of machine selection process and corresponding tools that allow a user to select which of several machines the user wishes to interrogate and/or control and hence are more complex that single machine interfaces that can automatically provide information to an operator.
Furthermore, in the case of multi-machine interfaces there is always the possibility that an operator may inadvertently select one machine believing that the operator has selected another machine for monitoring or control. Here, as above, the possibility for an unintended and costly result is great.
Second, as in most businesses, in an automated facility, there are many different types of employees and machine access and control requirements for the employee types are very different. For instance, a janitor likely has no need to access machine information or control machine operation, a maintenance engineer will require access to certain machine information and control capabilities and a process engineer may require access to a completely different set of machine information and control capabilities. Systems have existed for a long time (e.g., password protection, biometric comparison, etc.) that can restrict information access and control to specific authorized personnel. Unfortunately, these systems generally require relatively complex and expensive interface devices (e.g., a complete keyboard or some type of biometric scanner). As indicated above, in automation most interfaces are minimized to reduce costs and hence the added security that comes with restricting access and control to those having a need to access and control are often foregone.
One solution to the above problems that has been used in the automation industry is to provide hand held devices (HHDs) to machine operators having a need to monitor and/or control facility machines. (Unless indicated otherwise all portable information devices hereinafter will be referred to as HHDs, including PDAs, laptops, etc.). Here, an HHD, as its label implies, is a relatively small and portable device that can be carried around a facility by a machine operator. The HHD is typically provided with a small display screen, a set of buttons or a full keyboard to enable information interchange, a processor, a memory and a connection cable having a distal end configured to be received by a machine port. Each facility machine is provided with a machine port for receiving the HHD cable. To link to a local machine processor, the HHD cable is plugged into the machine port and establishes a one to one match where there is no ambiguity regarding which machine an HHD user is obtaining information for.
Here, information access and control can be restricted by restricting access to the HHDs. Thus, for instance, when a maintenance engineer enters a facility to perform maintenance duties, the engineer may check out an HHD from a central HHD location for use in the facility. After the maintenance engineer has completed his duties, the engineer may be required to check the HHD back into the central HHD location. To restrict access and control differently for different personnel there may be classes of HHDs where each class allows a user a unique set of access and control privileges (i.e., a maintenance HHD may have a first set of capabilities while a process control HHD may have a second set of capabilities).
Unfortunately the HHD solution described above also has several shortcomings. First, the manual process of linking an HHD to a machine processor is time consuming, burdensome and costly. Again, while one or a small number of linking processes may not seem burdensome, where the process has to be repeated several hundred times during an operator's shift, the combined linking tasks become excessive. In addition, in this case there may be a safety risk where an HHD becomes untethered from a machine in some way. One other problem with these types of plugs in HHDs is that access ports for receiving a tether may not always be readily accessible.
Second, where several hundred links may have to be made during a given day, the wear and tear on machine communication ports and HHD cable can be excessive and require either routine replacement or an extremely robust and expensive mechanical linking system.
Third, despite support for some customization regarding the types of information and control provided to a facility employee by way of configuring HHDs as a function of the type of employee that will use the HHD, there is no easy way to allow an employee to customize the appearance of information and control tools provided by the HHD. For instance, one maintenance engineer may want a first set of information presented in a first format while another maintenance engineer may want the same first set of information presented in a second format completely different than the first format.
Fourth, any system that requires an HHD to be tethered to a machine in order to obtain information related to the machine or to control the machine restricts operator movement and may not allow an operator to move into particularly advantageous positions to observe machine operations. Also, in this regard, a mechanical tether is cumbersome to manipulate and therefore is bothersome.
Industries outside industrial automation have faced problems similar to those faced in industrial automation and have devised some solutions that are suitable to the respective industries. For instance, in the medical industry, it has been recognized that the ability to obtain information about a patient automatically upon entering the patients room is advantageous. In a medical facility, a process that requires a physician to manipulate a patient's arm to identify a patient ID on a wristband or the like and then enter the patient ID into an information device to obtain the patient's medical history is burdensome. The process may disturb a sleeping patient, requires that the physician come in close proximity to the patient, is subject to human error and is time consuming. The process is particularly burdensome in emergency situations where time may be of the essence.
European patent application No. 0,992,921 (hereinafter “the '921 reference”) entitled “Computer Access Dependent On Location of Access Terminal” which was filed on Sep. 21, 1999 teaches a facility system wherein a separate wireless access point is positioned within each facility room for communicating with physician specific wireless HHDs located within the room. The '921 reference teaches that a physician identifier is stored in the HHD and, when an HHD is sensed within a room, the access point automatically obtains the physician identifier from the HHD, determines a degree of access (i.e., authorization) associated with the physician identifier, accesses information associated with the room (i.e., information associated with a patient within the room) and then transmits a sub-set of the patient information consistent with the physician's degree of access to the HHD for display.
The '921 solution works well in a facility that can easily be divided into cells separated by walls (i.e., patient rooms) and where there is only one set of information (i.e., information related to a single patient) associated with a particular cell. However, if a plurality of patients are located within a single room the '921 reference system cannot determine for which of the plurality of patients a physician seeks information. It is unclear how the '921 reference would resolve the quandary regarding which patient information to provide to a physician when more than one patient resides in a room. The '921 reference presents a problem where a physician may end up reviewing information corresponding to one patient while examining a different patient in the same room—clearly an unacceptable situation. In the context of an automated facility the '921 reference could not be used to select information corresponding to one machine out of a plurality of machines in a room for delivery to an HHD.
In addition, the '921 reference fails to teach or suggest any type of location specific equipment control. Failure to discuss equipment control is not surprising given the relatively course location resolution contemplated by the '921 reference.
Moreover, the '921 reference system and other systems of the same ilk require a relatively large number of access points to provide even the relatively coarse location resolution capabilities contemplated. System cost increases along with component count and therefore systems like the '921 reference system are relatively expensive.
In the office automation industry, U.S. Pat. No. 6,359,711 (hereinafter “the '711 patent”) which issued on Mar. 19, 2002 and is entitled “System and Method for Supporting A Worker In A Distributed Work Environment” teaches a system where, like the '921 reference, a single access point is located within each room in a facility. The '711 patent teaches that HHDs (i.e., laptop computers) used by specific users are provided with user identifiers. A system database correlates user identifiers with information related to applications that the specific users subscribe to or have authorization to use. In addition, the database also includes information related to office equipment located throughout a facility where the equipment is associated with specific applications. For instance, a word processor application may require access to a printer, a window treatment control application may require access to motorized blinds and an HVAC application may require access to a thermostat control.
When an HHD is brought into a room, the access point senses the HHD, obtains the user identifier therefrom, accesses the database to identify applications associated with the user identifier, identifies which office equipment types the identified applications must access, locates the single instance of each identified office equipment type that is closest to the access point and then creates a control link between the laptop and the identified equipment instances.
While suitable for an office environment, the '711 patent control scheme is not suitable for an industrial automation environment for several reasons. First, the '711 patent system, like the '921 reference system, relies on clearly delineated and identifiable facility cells (i.e., rooms) and a single access point in each cell. Like the '921 reference, the '921 patent system cannot determine relative proximity between the HHD and a plurality of machines located within a single room. For instance, where an HVAC control, a printer and a laptop are located in the same room, the '711 patent cannot determine if the laptop is closest to the HVAC control or the printer.
Second, the '711 patent system teaches linking a laptop to the closest instance of each required equipment type independent of whether or not the instance is proximate the HHD. For instance, in the case of a word processor application requiring a printer, the '711 patent system locates a closest printer to an access point and enables control of the located printer irrespective of the distance between the printer and the laptop (i.e., the access point). Here, the printer may be five rooms away from the HHD and hence from the person operating the printer. This type of “blind” control is acceptable in the case of a printer application where the end results of an imperfect printing process is minimally costly. However, in the case of automated control of machinery, as indicated above, such blind control often cannot be tolerated.
Third, a system like the '711 patent system would cause confusion in an industrial control environment. To this end, while a particular user may have clearance to observe machine information corresponding to several different machine types and to control various machine types using various applications, simultaneously and automatically presenting information or controls corresponding to two or more machine types at a time would be confusing where only a single machine type can be controlled at any one time.
What is really needed in the industrial automation environment is a system that can be used to clearly associate a wireless HHD within a facility with a single facility machine for monitoring and control. One way to accomplish this HHD-machine associating task is to identify machine zones adjacent each facility machine, determine when a wireless HHD is within one of the zones and then provide machine information to the HHD corresponding to the machine associated with the zone for presentation to the HHD user. This method of associating cannot be achieved without precise location resolution.
World patent application No. WO 00/50919 (hereinafter “the '919 reference”) which is titled “Method and Computer Readable Medium for Locating and Tracking a User in a Wireless Network Using a Table of Digital Data” teaches one system that can be used to relatively accurately determine location within a specific space or within a room. To this end, the '919 reference teaches a plurality of base stations or access points can be installed at locations within a facility. The access points each transmit signals of known strength to mobile HHDs within the facility. The strengths of the signals decrease as a function of distance traveled. The HHDs each receive the transmitted signals and, based on signal strengths of several of the received signals, determine the location of the HHDs within the facility.
World patent application No. WO 02/054813 (hereinafter “the '813 reference”) titled “Location Estimation in Wireless Telecommunication Networks” teaches a location system similar to the system described in the '919 reference that relies on signal strength to determine location of a portable device within a facility. The '813 reference, however, applies a statistical model to the received signals to, supposedly, yield a far more accurate device location.
While each of the '919 reference and the '813 reference teach location determining systems that have better resolution than the room based systems described in the '921 reference and the '711 patent, it is likely that even with the increased resolution capabilities afforded by the '919 reference or the '813 reference, the location resolution requirements for a secure wireless industrial control cannot be achieved for several reasons. First, even where a signal strength based system supports relatively accurate location resolution throughout most of a facility, it may be that an unusually large number of moving metallic machines reside in certain facility areas that may introduce errors into transmitted signals thereby appreciably affecting received signal strengths. In this case, at least in areas including unusually large numbers of machines or machines having odd layouts, location position may not be accurately determined using the '919 and '813 reference systems.
Second, many industrial facilities are laid out according to space saving schemes that require adjacent machines to be juxtaposed relatively close to each other. In these cases machine zones corresponding to two or more adjacent machines may overlap so that, even a properly operating high resolution location determining system could not distinguish which machine information is sought in the overlapping region. Thus, for instance, assume that a location determining system identifies that an HHD is located in a space that is overlapped by three adjacent machine zones, here, the HHD may be provided with information corresponding to any one of the three machines corresponding to any one of the three overlapping zones.
Third, even where machine zones can be selected so that the machine zones do not overlap, many practical location determining systems may not be accurate enough to distinguish between adjacent zones. For instance, locating systems based on signal strength may only be able to distinguish general location within a room such as in which of four room regions an HHD resides or in which of sixteen equi-sized room regions an HHD resides or in which of 100 facility regions an HHD resides where each of the regions may includes several different machines.
In addition, there may be situations where a single area is associated with more than one machine zone. For instance, a transfer line may move items along a path adjacent thirty different machines. In this case it may make sense to be able to observe information corresponding to the transfer line at any location along the line and to observe information for each machine only adjacent each machine. Similarly, it may make sense to enable an HHD user to observe a machine or machine line layout map for a facility area from any space within the area or to observe machine specific information for one or more machines proximate an HHD user's specific location within the area.
Thus, it would be advantageous to have a system that could be used to unambiguously identify a machine for which information is sought and then associate an HHD and the machine so that machine specific information is obtainable with minimal HHD operator effort.